Retinal ischemia has been produced by exposing young animals to an oxygen-enriched environment. Following the removal to room air, a secondary vasoproliferation results. These studies are being quantitated to standardize the experimental model for future bio-assay of vitreous homogenates and retinal extracts in an attempt to isolate factors that re related to abnormal vasoproliferation. these studies, on this experimental model of retinal ischemia and vasoproliferation, are relevant to the basic problem occurring in several proliferation retinopathies.